This instructable documents my process for rebuilding the tail lights of my early 1970's Coleman pop-up camper. I was unable to find appropriate replacement parts locally nor online, so I reconfigured them to take new bayonet sockets (BAY15d). These take dual filament bulbs and produce the tail light (when headlights on), brake lights, and turn signal functions.
Step 1: Assess the Situation
In my case, there were other issues beyond the rusted out mounts with iffy electrical connections, but I'm just going to cover this part here.
Remove the lens cover from the housing. Mine has two pan (or dome) head screws to hold it to the housing and a very aged cork gasket that held on a little. I suppose the recessed nature of this design allowed the housing to be smaller, the business end of the bulb in the center of the lens, and any water that entered the housing to be below the electrical connections. However, once the gasket on the lens failed, it also allowed water to sit in the steel well and cause corrosion.
In my case, one side was so corroded, the metal was broken and the bulb and its immediate socket flopped around during travel. The other side wasn't quite so bad, but the corrosion was still enough that it required more than just cleaning of the electrical contacts to get reliable operation.
Step 2: Disassembly
The metal part of the assembly was held to the plastic box by three rivets, two of which also held the plastic housing to a tab on the sheet metal body of the camper. There were two more rivets in the top of the housing that held it to the camper body at a tab inside the upper part of the opening.
Sheared the rivet heads off with a cold chisel and popped most of the location free with a nail punch. A few were not to easily persuaded and had to be drilled out.
It may be obvious, but it's not a bad idea to take some photos and maybe make a sketch of the wiring before you cut things and remove them too far from the camper (and take two weeks to get back to the project).
Step 3: Buy Replacement Socket and Bulb
Each side needs a new socket and bulb. The bulbs have a BAY15d base, which has two pegs at different heights to align it in the socket. The three auto parts stores I went to locally had a huge variety of replacement sockets. I chose something similar to this one: Stop, Turn, Taillight Socket.
Step 4: Socket Base Rebuild: Lay Out Cuts/Holes
Armed with the original parts and the replacement stop/turn/taillight socket(s), I started laying out my cuts and holes to be drilled. I had a random painted steel cover from some sort of electrical box in my scrap pile, and I decided to use it for the base material for the mounting plate.
My plan (and what I did) was to replace the whole steel socket well thing with a simple flat sheet of steel that allowed the new socket to recess into it and orient the lighted portion of the bulb in the center of the red tail light lens. I traced the original piece to match the outer dimensions and attachment points. I located the bulb in the center left-to-right and near the exterior of the housing, as in the original. And I marked a large enough hole for the main cylindrical portion of the socket to pass through, but not the flange at the top.
Step 5: Socket Base Rebuild: Cut Socket Hole
I have to say that one of my favorite tools is my knockout hole punch. It's elegant and satisfying to use. Anyway, I drilled the center hole for the alignment bolt that draws the pieces together, shearing through the steel plate.
This is a perfect time to teach your daughter how to use a drill press, if you have a daughter and a drill press.
Regardless, the knockout hole punch threads onto both sides of the plate through the center hole and a handful of turns with a reasonable wrench leads to the double crack of both halves of the circle shearing fully through the plate.
Step 6: Socket Base Rebuild: Cut and Drill
I cut the piece out of the steel plate with a jigsaw and a metal-cutting blade, then cleaned the edges with metal files, and drilled the remaining holes for the attachment screws.
One hole not shown here is for a sheet metal screw that holds the socket firmly to this plate. I eyeballed its placement with the socket inserted into the center hole. You can see it in later photos, but the goal is to have the head of the sheet metal screw make contact with the outer edge of the socket flange and hold it down.
Step 7: Socket Base Rebuild: Assemble, Temporarily Rewire, and Test
I realized that I should file/sand some of paint off of the plate for the electrical connections. This lamp socket is two-wire (one for each filament) and it requires grounding through the case to the trailer ground (frame/body). The metal plate is grounded to the body via the mounting screws (originally rivets) to the attachment tabs in the body opening.
Once everything was temporarily rewired and grounded, I tested that the taillight, stop, and turn signal functions were all correct.
Step 8: Socket Base Rebuild: Reassemble, Test, and Drive to Camp!
It's crucial to have the wires routed through all appropriate parts before the electrical connections are made. I remind myself that a dozen times every project like this, and there are still a disturbing number of incidents where I have to cut the wiring back apart to route things properly.
This is a good time to cut new cork gaskets. I haven't done it yet, but it'll happen soon.
Once everything is back where it should be, test again. Drive it around a little, test again, and then have someone else watch to make sure it all works properly while you're driving. For everyone's safety, please.
Then, go somewhere pretty and camp! (Like Hartman Creek State Park in Wisconsin)